Hydraulically operated vehicles such as loaders are used generally to transfer bulk material from a stock pile onto a transport vehicle such as trucks or railroad cars. In such vehicle loading applications, it is essential that the transport vehicles are loaded to, but not over, their maximum rated legal capacity. Underloading causes inefficiency in the material hauling cycle and underutilization of the transport vehicles. The penalty for overloading a truck is the additional maintenance cost for the overburden and extra wear on the truck tires and suspension system. Furthermore, the overloaded material may need to be unloaded to decrease load weight, causing additional expense to the hauling operation.
It is easily recognized that payload measurement is also desirable as a measure of the material hauling operation productivity. The ability to accumulate the weight of the material loaded during a single shift, during a twenty-four hour period, or during any increment of time is invaluable to an operations manager.
Recent attempts to provide accurate payload monitors have focused on sensing hydraulic pressure within the lift hydraulic cylinders. The hydraulic pressure through various methods has been used as a direct indication of the payload weight. However, it has become apparent that due to tolerances within the pressure and position transducers, each machine had different results and each had to be individually configured. Also, it become apparent that each sensor tended to drift over time. Thus, each machine had be reconfigured at various points in its life cycle in order to ensure accurate payload measurements.
The present invention is directed at overcoming one or more of the problems as set forth above.